1. Field of the Invention
The present invention relates to a liquid crystal display device (LCD), and more particularly to a hybrid switching mode LCD.
2. Discussion of the Related Art
In a thin film transistor liquid crystal display device (TFT LCD), while it is desirable and required to make a large scale LCD, a problem exists in that the contrast ratio thereof changes according to a viewing angle. In order to solve this problem, various LCDs, such as twisted-nematic (TN) LCD including an optical compensation film and multi-domain LCD have been introduced. In these LCDs, however, problems still exist in that a contrast ratio is decreased and a color shift is generated according to a viewing angle.
For realizing a wide viewing angle, an in-plane switching mode liquid crystal display device (IPS LCD) is also being proposed.
FIG. 1A is a plan view of a conventional IPS LCD. The IPS LCD comprises a data bus line 1 and a gate bus line 2 which are arranged on a first substrate to define a pixel region. A common bus line 5 is arranged parallel to the gate bus line 2. A TFT is positioned at a crossing area of the data bus line 1 and the gate bus line 2. Data electrodes 19 and common electrodes 11 are arranged parallel to the data bus line 1.
FIG. 1B is a sectional view taken along the line Ixe2x80x94I of FIG. 1A. As shown in FIG. 1B, the TFT comprises a gate electrode 10 which is connected to the gate bus line 2 on the first substrate 3, a gate insulator 13 including SiNx or SiOx deposited on the gate electrode 10, an amorphous silicon (a-Si) layer 15 formed on the gate insulator 13, a n+ a-Si layer 16 formed on the a-Si layer 15, and source/drain electrodes 17, 18 formed on the n+ a-Si layer 16, which are respectively connected to the data bus line 1 and data electrode 19. The common electrode 11 in the pixel is connected with the common bus line 5 on the first substrate, and the data electrode 19 is connected with the drain electrode 18 of the TFT on the gate insulator 13. On the TFT, data electrodes 19, and gate insulator 13, a passivation layer 20 including SiNx or SiOx is deposited over the substrate, and a first alignment layer (not shown in the figure) is formed thereon and alignment direction is determined.
Further, on a second substrate 4, a light shielding layer 6 preventing light leakage, a color filter layer 7 having color filter elements of R, G, and B, and an overcoat layer 8 are formed in order.
In such conventional IPS LCD, however, there are voltage losses by the passivation layer between the data electrodes and the common electrodes and the gate insulator. Therefore, in order to drive liquid crystal molecules smoothly, a high voltage should be applied to the LC layer. Moreover, because the electrodes are formed on one substrate, such defects as cross talk and residual image occur. Also, because the common electrode is made with the same material as the gate electrode, for example, an opaque metal such as Cr, Ta, and the like, its transmittance ratio decreases.
Accordingly, the present invention is directed to a hybrid switching mode liquid crystal display device that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a hybrid switching mode LCD having a low driving voltage of an LC layer.
Another object of the present invention is to provide a hybrid switching mode LCD where at least a pair of electrodes which apply an in-plane and inclined electric field are formed on upper and lower substrates, respectively.
Another object of the present invention is to form transparent electrodes on one side of the substrate and improve the aperture ratio of the LCD.
Additional features and advantages of the invention will be set forth in the description which follows and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, the present invention provides a hybrid switching mode LCD (HS mode LCD) comprising a first substrate, forming at least a pair of electrodes applying an in-plane electric field, and a second substrate corresponding to the first substrate, forming a group of electrodes corresponding to the electrodes, so that a perpendicular and an inclined electric fields are applied between the substrates, and the driving voltage of an LC layer decreases.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.